Wind turbines are exposed to significant operational stresses from wind, rotational forces and the weight of a plurality of blades. The operational stresses are often amplified by environmental temperatures with extremes depending on geographical location. The materials used for the components of the wind turbines must be able to withstand operating stresses and strains throughout the range of temperatures.
Due to their strength, toughness, castability and machinability, ductile iron (cast nodular iron) alloys have also been used to produce wind turbine components. The strength of cast iron has been improved remarkably by the development of spheroidal graphite cast iron, i.e. ductile cast iron, but its ductility and impact resistance are still behind those of steel, making steel the desirable material for a variety of components, including gearbox components. To improve the mechanical properties of ductile iron, attempts at refining of the graphite nodules of the alloying of special elements have been made, but not succeeded yet in obtaining sufficient results. In addition, these processes may have such disadvantages as complicated or energy intensive processing.